The springs on the PP clamp the PP surface to the FW. THe FD is trapped between them like its in a vise. The TO bearing pulls one of the jaws of the vise open, giving clearance at friction surfaces, when you depress clutch pedal. It first must overcome the force of the preloaded springs, then more force to compress the springs and pull the PP off the FD.

 

You know what?.. I feel like an idiot now because it's so obvious.

That ring (the PP) actually moves in and out. If you look at the clutch assembly (housing and PP) it doesn

 

Ypu've seen the light.

 

I'm an electronic engineer. Not mechanical